Eloq tweeted that he heard SXSW did a lot to try to help his situation, but "the customs guy didn't know about the SXSW visa rules apparently."

It's unclear what kind of visa Eloq was using. He has since made it back to Denmark.

Eloq is one of a growing number of international artists who have been unable to make it to the festival, the music portion of which runs this week, because of the visa issue.

Members of the Italian group Soviet Soviet and their London-based drummer were denied entry to the country last Wednesday at Seattle-Tacoma International Airport, the band said in a statement.

They were held in jail cells and deported the next day.

The band members said they showed passport control their Visa Waiver Program information, along with a letter from their label showing they would be performing a series of concerts for promotional purposes and wouldn't be receiving any payment, as well as an invitation from SXSW.

The waiver program allows citizens of nearly 40 countries to travel to the U.S. without having to obtain a visa, NPR reported.

"We knew that if we were to receive any compensation we would have had to apply for work visas," the band's statement said. "This was not the case and the people we spoke to for information told us we would be fine."

Egyptian-Canadian band Massive Scar Era said three of its members were denied entry over the weekend in Vancouver because their B-1 Visas were not accepted, Billboard reported.

Massive Scar Era said on Facebook that they were carrying paperwork from SXSW showing they were traveling under a B-1 visa.

The B-1 visa is typically issued to tourists who aren't legally allowed to work during their visit. Most artists entering the country have a performance visa, a P-1, but in the past artists performing for free at events such as SXSW have been able to use B-1 visitor visas.

In an advisory, U.S. Customs and Border Protection officials said Monday that artists would need a P-1 if they planned to perform in the U.S. at promotional events like SXSW, Billboard reported.

A spokesperson for SXSW told Billboard that event officials "know about the situation" and "have spoken to the artists" but are declining to comment on the visa issue.

Chilean band Trementina was also scheduled to perform at several events at the festival, but the band said they received an email stating they had the wrong visa to enter the U.S., Austin 360 reported.

"We've heard about Soviet soviet situation when they arrived to the U.S.," the band said in a Facebook post Sunday. "In some way, we feel calm because we didn't have to be in that kind of situation, but anyway we don't know what else we can do."